Combine lemon juice, vinegar, garlic, lemongrass, dried red pepper, brown sugar and salt in a small saucepan. Bring to a simmer and stir until brown sugar is dissolved. Let cool.
Place chicken in a gallon size ziploc bag. Pour marinade over chicken. Seal and store in fridge for 4 hours or overnight.
Clean and oil your grill. Heat to medium high on one side and cool on the other.
Mix oil and ketchup in a bowl.
Place chicken skin side down on hot grill side. Brush back of chicken with glaze. Close lid and cook for 10 minutes or when ready to release from grill.
Flip and move to cool side of grill. Base again with glaze. Let cook until meat thermometer reaches 72C or 165F.
